Centering device



Nov. 22, 1960 A. KUNZLER 2,960,806

csmamc DEVICE Filed July 13, 1959 2 Sheets-Sheet 1 \i j Z \-z& 51 a J J a 48 Q Q Q Q) 4:5

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NOV. 22, 1960 ER 2,960,806

7 CENTERING DEVICE Filed July 13, 1959 2 Sheets-Sheet 2 IN VEN TOR.

United States Patent CENTERING DEVICE Alex Kunzler, Seattle, Wash., assignor to Brunswick Corporation, a corporation of Delaware Filed July 13, 1959, Ser. No. 826,761 6 Claims. (Cl. 51237) This invention relates to a centering device for an object and more particularly to apparatus for centering a mandrel nose.

An object of this invention is to provide new and improved mandrel centering apparatus.

Another object of the invention is to provide mechanism for centering a mandrel relative to a machine ele ment such as the upper bearing plate of a grinder turntable in which the support carries a center post which receives and centers a mandrel base and .three equally spaced positioning devices are disposed about the center post and engage the under side of. the mandrel whereby the nose of the mandrel is centered by adjusting the height of thepositioning devices. and the exact position of a mandrel is determined by setting the positioning devices according to a gauge associated one with each of the devices. V

Another object of the'invention'is to provide apparatus as defined in the preceding paragraph in'.which each of the positioning devices comprises a base and an upper supporting plate with an actuator disposed therebetween and having ball supporting cages on either side thereof and each of the cages having openings to receive magnets to hold the positioning device together, said actuator and base having co-acting sloped faces whereby longitudinal shift of the actuator will vary the height of the top plate of the device to vary the position or the mandrel.

Further objects and advantages will become apparent from the following detailed description taken in connection with the accompanying drawings in which:

Figure 1 is a perspective elevational view with the mandrel broken away to show the center post associated with the mandrel;

Figure 2 is a vertical section of a positioning device on an enlarged scale and taken generally along the line 22 in Figure 1; t

Figure 3 is a plan view of the positioning device shown in Figure 2, with parts broken away;

Figure 4 is a vertical section taken line 4-4 in Figure 3; and

Figure 5 is a fragmentary vertical section similar to Figure 4 and showing part of one positioning device which is dilferent from that shown in Figure 4.

While this invention is susceptible of embodiments in many different forms, there is shown in the drawings and will herein be described in detail an embodiment of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the embodiment illustrated. The scope of the invention will be pointed out in the appended claims.

In the manufacture of articles such as radomes in which the article is made of glass fiber filaments bonded together by a suitable resin, it is a usual practice to form the radome on a mandrel such as the mandrel shown in the drawings whereby the article will have the desired internal shape. The radome while still on the mandrel generally along the 2,969,8d5 'Patented Nov. 22, 1960 10 normally will undergo certain finishing operations, such as grinding, to bring the radome to the desired dimensional characteristics, such as thickness of wall and external dimensions. For this machining to take place, it is necessary that the mandrel be mounted with the base and the nose, as indicated at 11, disposed co-axially with the axis of rotation of a machine element 12 which, as disclosed, is the upper bearing plate of grinding machine.

The mandrel 11] is properly centered at its base 13 by the co-action of a central opening 14 in the base which fits onto a center post 15 on the machine element 12 with a light interference fit. The mandrel base 13 has three radially extending legs 16, 17 and 18 each of which has an opening 19 whereby the openings 19 are equally spaced apart and disposed radially outwardly of thecentral opening 14 in the mandrel base.

It will thus be seen that with the mandrel 10 located on the center post 15, the mandrel nose 11 may be centered by properly locating the height of the mandrel base openings 19 relative to the machine element 12.

Means for adjusting the height of the mandrel base openings 19 and thus centering the nose 11 of the mandrel comprises three positioning units or devices 20, 21 and 22 mounted on the machine element 12 in a circular arrangement disposed radially of the center post 15 and equally spaced apart to be disposed adjacent the three openings 19 in the mandrel. Each of the positioning units carries a steel ball 23 which engages in the adjacent mandrel opening 19 whereby upon proper adjustment of the height of the three balls 23 the mandrel nose 11 may be properly centered. Each of the posi-, tioning units 20, 21, 22 are basically the same and the positioning mechanism 22rwill be more fully described. by reference to Figs. 2-4.

The positioning unit 22 has a unit base 25 which is attached to the machine base 12 by bolts passing through the slots 26 and 27 at the sides thereof. A top plate 28 is spaced from the unit base 25 and is formed with an opening 29 in which an insert 30 is positioned to hold the ball 23. A shiftable actuating member 31 is disposed between the unit base 25 and the top plate 28 and is movable relative to the latter parts by being separated from each by means of ball-bearing cages 32 and 33 each having balls 32a and 33a, respectively. The upper cage 32 is disposed between the shiftable member 31 and the top plate 38 and the cage 33 is located between the underside of the shiftable member 31 and the unit base 25. The parts of the positioning unit are maintained in lateral relation by the down-turned legs 34 and 35 on the top plate 28 which extend downwardly in partially lapping relation with the shiftable. member 31 and the upwardly extending legs 36 and 37 on the unit base 25 which extend upwardly in partially lapping relation with the shiftable member 31.

The positioning unit 22 functions as a drive dog to transmit rotation of the machine element 12 to mandrel 149 'by having the sides of the shiftable member 31 in engagement with the legs of the top plate 28 and the unit base 25 while the other two positioning units 20 and 21 have some side play therein so that the pattern of the holes 19 in the mandrel may vary slightly. This side play is permitted, as shown in Figure 5, by having some clearance between the shiftable member 31 and the legs 35 and 37 in the positioning units 20 and 21.

The positioning uni-ts are held together by means of a pair of magnets 40 and 41 mounted in each of the ball cages 32 and 33 with the magnets 40 and 41 inserted into the cage with reversed polarity. With the cages 32, 33 being formed of brass the magnets 40 and 41 form a magnetic flux path through the shiftable member 31 as well as the unit base 25 and top plate 28 whereby to maintain the parts assembled.

The shiftable member 31 has its lower face 42 formed with a slight incline and an upper face 43 of the unit base 25 has the same incline whereby longitudinal shift of the shiftable member 31 will result in varying the heighth of the top plate 28 and the ball 23 which engages the mandrel opening 19.

Means for longitudinally shifting the shiftable member 31 comprises a shaft 44- rotatably mounted in an opening 45 in the unit base 25 and being threaded at one end thereof, as indicated at 46, whereby a bushing 47 fastened to a leg 48 of the shiftable member 31 and threaded on the threads 46 will be shifted longitudinally of the shaft 44 upon rotation thereof. The shaft 44 is rotated by engagement of a tool with the end 50 of the shaft, and is held against longitudinal movement by a flange 51 at one end thereof and a bushing 52 at the other end thereof held on the shaft by a nut 53.

In this manner the heighth of the positioning units may be adjusted while a mandrel is supported thereon. Means are provided for locating a mandrel in exact position and this is determined by a gauge 55, there being a gauge associated with each of the positioning units 20, 21 and 22. Each gauge 55 is mounted on a leg 56 attached to the unit base 25 of a positioning unit and has a movable stem 57 which extends upwardly to a position to engage the underside of the mandrel base and operates a suitable dial indicator 58.

It is thus possible to exactly position a mandrel and repeat this position each time the mandrel is mounted on the machine base by adjusting each positioning unit to give the predetermined dial indicator setting for each of the gauges 55.

In the operation of centering a mandrel 10 and particularly the nose 11 thereof, the mandrel is first placed over the machine element 12 and the central opening 14 placed on the center post with the openings 19 in the mandrel base mounted on the steel balls 23. Each of the positioning units is operated by rotation of the shafts 44 to provide a certain gauge reading and has the nose of the mandrel positioned properly as a result thereof.

The dial indicators permit the use of any number of mandrels with the same centering device. Once a mandrel has been centered, the indicator readings of all three units are tabulated on a chart. Since the mandrels are numbered, their settings can be repeated as desired simply by referring to the chart. Therefore, the positioning of each mandrel each time that it is set up is controlled by the dial indicators. By means of this setting method, any number of production mandrels, with bases of limited accuracy may be mounted in the machine with great accuracy.

I claim:

1. Apparatus for centering a mandrel having a base with three circularly disposed equally spaced apart openings comprising, a machine base having mandrel nose positioning mechanism including three mandrel engaging units circularly disposed and adjustable in height to properly align the mandrel nose, each of said units comprising a unit base having an inclined upper face, a top plate spaced from the unit base and carrying a member engageable in one of said three openings, an operating member disposed between the unit base and the top plate with the undeside thereof having the same inclination as said upper face, a pair of ball-bearing cages positioned one on either side of said operating member to permit longitudinal shift of said operating member relative to the unit base and top plate, magnets mounted in said cages holding said base and top plate together, and means for longitudinally shifting said operating member to vary the height of said top plate comprising a rotatable memher mounted in said unit base, and connections between said rotatable member and the operating member whereby rotation of said rotatable member results in longitudinal shift of said operating member.

2. A mandrel centering device comprising, a center post onto which a mandrel base fits, and three equidistantly spaced positioning mechanisms disposed radially about said center post each engageable with the mandrel outwardly of said center post and adjustable in height to center the nose of the mandrel, means associated with each positioning mechanism and engageable with the mandrel to determine the mandrel location, and means for adjusting the height of each positioning mechanism while supporting a mandrel.

3. Apparatus for centering a mandrel having a base with a central opening and three equally spaced apart openings outwardly of the central opening comprising, a machine base having an upstanding center post to engage the central opening and center the mandrel base, and means for centering the nose of the mandrel comprising three positioning units disposed on the machine base about the center post and outwardly thereof and each engageable in one of said three openings, and means for adjusting the height of a positioning unit while a mandrel is supported thereon.

4. A centering apparatus as defined in claim 2 in which each of said positioning units comprises a base supported on the machine base and a top member spaced from the unit base and a member positioned between the unit base and top member shiftable to vary the spacing between the unit base and top member to adjust the height of the top member, and said height adjusting means includes adjustment mechanism connected to said shiftable member.

5. Apparatus for centering an object having a nose and a base with a central opening and three equally spaced apart openings outwardly of the central opening comprising, a machine element having an upstanding center post to engage the central opening and center the object base, and means for centering the nose of the object comprising three positioning units disposed about the center post and outwardly thereof and each engageable in one of said three openings, means for adjusting the height of a positioning unit while an object is supported thereon and means for indicating the distance between the machine base and the object base.

6. Apparatus for centering a mandrel having a base with a central opening and three equally spaced apart openings outwardly of the central opening comprising, a machine element having an upstanding center post to engage the central opening and center the mandrel base, mandrel nose positioning mechanism comprising three mandrel engaging units disposed about the center post and adjustable in height to properly locate the mandrel nose, each of said units comprising a base, a top plate spaced from the unit base and carrying a ball engageable in one of three said openings, an inclined operating member disposed between the unit base and the top plate, a pair of ball-bearing cages positioned one on either side of said operating member to permit shifting of said operating member relative to the unit base and top plate, and means for shifting said operating member to vary the height of said top plate.

References Cited in the file of this patent UNITED STATES PATENTS 977,327 Patcliffe Nov. 29, 1910 2,465,497 Turrettini Mar. 29, 1949 2,722,867 Dackor et al Nov. 8, 1955 

